Homalium laxiflorum (Tul.) Baill.

Wendy L. Applequist, 2016, Revision of the Malagasy species of Homalium sect. Eumyriantheia Warb. (Salicaceae), Candollea 71 (1), pp. 33-60 : 44-45

6. Homalium laxiflorum (Tul.) Baill. in Bull. Mens. Soc. Linn. Paris 1: 575. 1886.

Ξ Myriantheia laxiflora Tul. in Ann. Sci. Nat., Bot. sér. 4, 8: 66. 1857 [as Myrianthea ].

Lectotypus (first step, designated by Sleumer, 1973: 326): Madagascar: sine loc. [Foulpointe?], s.d., fl., du Petit-Thouars s.n. ( P)

Lectotypus (second-step, designated here): sine loc . [Foulpointe?], s.d., fl., du Petit-Thouars s.n. ( P [ P04705839 ]!; isolecto-: P [ P04705842 ]!, P-JUSS n°14412 image seen) . Syntypus: Madagascar: sine loc. [Foulpointe?], Chapelier s.n. ( P [ P04705840 ]!)

Tree to 14 m tall, 20 cm dbh, bark dark; large twigs dark brown (to gray, often streaky or patchy); young twigs grayish, glabrous (sparsely short-pubescent at apices); stipules broadly deltoid to deltoid, 0.7-1.4 mm, glabrate. Leaves often subopposite or opposite distally, mostly alternate proximally; petiole (1-)5-12(-20) mm, glabrous (sparsely short-pubescent); blade obovate to narrowly oblong (elliptical, oblanceolate, broadly obovate), (3-)5-10(-11.5) × (1.4-)2.3-4.9(-5.7) cm; base convex to cuneate (seldom to rounded); apex irregularly rounded to emarginate (rounded-obtuse, very rarely cuspidate); margins entire to minutely toothed, often somewhat revolute, with 1 to several glands at base or along whole leaf margin; abaxial surface glabrous or glabrate, drying pale to medium brown (rarely greenish); adaxial surface glabrous or glabrate, drying darker brown. Inflorescences racemes (or pseudoracemes, with bracteoles often borne in the middle of the pedicels; rarely in part racemiform panicles with few 2-flowered branches), lateral, 4-9.5 cm, moderately short-pubescent to glabrous proximally, to densely or patchily pubescent distally; peduncle 1.5-5 cm, slender; pedicel (1-)1.5-5(-7) mm, densely short-pubescent; bracts broadly oblong to broadly ovate or suborbicular, (0.5-) 1-2 mm, moderately to densely pubescent (seldom to glabrate); bracteoles ovate (deltoid, oblong), (0.4-)1-1.5(-2.5) mm, pubescent (to glabrate). Flowers: sepals greenish to yellowish or whitish, 4(to 5), broadly oblong to broad-based obovate or oblong (rarely broadly elliptical) with a rounded apex, 3-5.5(-6.5) mm, abaxial surface densely (to moderately above) short-pubescent; calyx cup funnelform, densely short-pubescent; sepal glands yellow, roughly rectangular, 1-1.5 × 0.5-0.6 mm, upper surface glabrous; petals cream to white, greenish, yellowish or pinkish-white (to pinkish after flowering), obovate with a narrow base, irregularly rounded apex, 3.6-6.2 × 2.6-3.8 mm, normally longer than sepals (similar in length in abnormal, possibly immature flowers), abaxial surface densely pubescent especially towards base, adaxial surface glabrous; filaments 2-2.5(-3) mm, glabrous; anthers orange to yellow, 0.4- 0.5 mm; ovary shallowly conical to flat (becoming hemispherical), hispid (villous); styles 3-4(-5), 1.5-2 mm, basally hispid (villous). Seeds 1 per fruit, subglobose, to at least 3 mm.

Vernacular names and uses. – “Hagontoho mainty” (Réserves Naturelles 2470); “Hazoambo” (Raharimalala 169, Service Forestier 5 6 2 1, 5 6 4 2, 9 5 1 3, 1 0 1 7 4, 1 3 6 8 7, 1 9 9 5 1); “Hazombaribe” (Réserves Naturelles 7973); “Hazombato” (Raharimalala 332, Réserves Naturelles 8034); Hazomby Ludovic et al. 560 “Hazonjia” (Service Forestier 5036); “Maimbo lambo” (Bernard 261, Raharimalala 279); “Malitsy anjahana” (Réserves Naturelles 4939); “Ramisaona” (Service Forestier 4902, 13687); “Ranjombitro” (Service Forestier 7093); “Rotramenaberavina” (Service Forestier 7349); “Tsitakonala” [Bm dialect] “Tsilaiha” (Réserves Naturelles 4547); “Tsitakonala” (Louvel 35, 199, Service Forestier 5734, 10052, 10070); “Tsitakotrala” (Rabenantoandro et al. 820); “Voatoala” (Cours 2978).

The wood of H. laxiflorum is used for construction (Service Forestier 19001).

Distribution, ecology and conservation status. – Homalium laxiflorum occurs primarily in littoral and sublittoral forests on sand, less often in low-elevation humid forest, occasionally on laterite. One collection from 671 m altitude (see below) is from the massif of Ankirindro, where a number of normally littoral species are reported to occur, possibly because the weathered quartzite sand substrate is similar to that of nearby littoral forests (G. Schatz, pers. comm.). The species is widely distributed, with recent collections demonstrating its presence in three provinces, and relatively common; therefore, despite ongoing threats to the remaining littoral forest, its preliminary assessment of conservation status should probably be “Least Concern” [LC].

Notes. – Sleumer (1973) designated “Aubert du Petit Thouars P & P-Juss 14 412” as lectotype of H. laxiflorum ; since this refers to at least two different sheets, one of them in the main herbarium collection at P, second-stage lectotypification is necessary. Only an inadequate image of the sheet in the Jussieu collection was available; it appears to contain material of rather poor quality, poorly labeled, and possibly heterogeneous. The sheet in the main collection at P is both better and more accessible, and is therefore preferred over the P-Juss sheet. In addition, Sleumer marked as “syn- & lectotype ” a sheet from Herbarium Richard [P04705842], labeled “ Myrianthea ”, “ Madagascar ” and, almost illegibly, “DupetitTh”. It may not be totally certain that this sheet represents the same collection; if it does, it is also inferior to the selected sheet. Sleumer stated that the type was from Foulpointe. None of the specimen labels provide locality data, but it is known that Petit-Thouars collected only around Fort-Dauphin (where H. laxiflorum does not occur) and on the “[east] coast near Fenerive” ( Dorr, 1997: 346), which would make Foulpointe a likely locality.

Homalium laxiflorum is the most frequently collected species in the section and is usually quite cohesive. Schatz et al. 3921, the collection from the mid-elevation quartzite massif of Ankirindro, has unusually large flowers and small, broad leaves with very short petioles (1-2 mm long, vs. at least 2.5 mm in all other specimens seen). This may represent environmentally induced variation or a genetically distinct variety, for which there is not sufficient material to permit formal description.

Additional material examined. – Madagascar. Prov. Antsiranana: Fkt. Antanandava ( Anjia ), 15°17’14”S 50°20’12”E, 25.II.2001, fl., Antilahimena et al. 705 ( MO) ; road between Sanjahana and Ambinaniny Mahorambo, 15°13’25”S 50°26’36”E, 8.VI.2001, fl., Antilahimena et al. 746 ( MO) ; Masoala, Fkt. Sahamalaza , Vinanivao , 15°52’S 50°19’E, 0-113 m, 12.XII.1995, fl., Aridy et al. 13 ( MO, P) ; ibid. loc., 15°49’S 50°18’E, 0-41 m, 22.II.1996, fl., Aridy & MoÏse 170 ( G, MO, P) ; ibid. loc., same date, Aridy & MoÏse 171 ( MO, P) ; Masoala, forêt d’Ambodipont , 15°44’45”S 50°19’25”E, 0-10 m, 15-20. III.1996, fl., Bernard 261 ( MO, P) ; ibid. loc., 3.X.1996, fl., Bernard 368 ( G, MO, P) ; Fampotatrely , Antalaha , Parc Masoala, 15°35’S 50°25’E, 0-50 m, 12.V.1996, post-fl., Bernard 291 ( MO, P) ; entre Antalaha et Sambava, côte NE, XI.1912, fl., Perrier de la Bâthie 6696 ( P) ; Masoala, Antsiraminanana , 15°28’S 50°26’E, 27.IX.1994, Rahajasoa et al. 631 ( P) ; Fkt. Sahafary, forêt d’Antsoha, 15°16’12”S 50°23’14”E, 50 m, 1.X.1997, fl., Ravololonanahary 111 ( G, K, MO) ; Fkt. Ambodirafia, 15°16’S 50°28’E, 23 m, 18.III.2001, fl., Razakamalala et al. 79 ( MO, P) ; 1.5 km W of Cap Est, 15°16’28”S 50°27’51”E, 35 m, 24.I.1999, fl., Schatz et al. 3802 ( G, MO, P) ; env. W d’Ambodipont-Isahana , entre Sambava et Antalaha , 17.IV.1967, fl., Service Forestier 27718 ( P). Prov. Fianarantsoa: forêt d’Ambahy , 20°45’44”S 48°29’20”E, 22 m, 31.I.2012, fl., Andriamihajarivo & Ravoahangy 1848 ( MO) ; env. de Farafangana, XII.1963, fl., Bosser 18691 ( MO, P) ; Mananjary, 21.XI.1908, fl., Decary 13784 ( P) ; Mananjary, III-IV.1909, fl., Geay 7260 ( P) ; ibid. loc., same date, fl., Geay 7393 ( P) ; ibid. loc., same date, fl., Geay 7400 ( P) ; ibid. loc., same date, fl., Geay 7412 ( P) ; ibid. loc., same date, fl., Geay 7568 ( P) ; ibid. loc., same date, st., Geay 7857 ( P) ; ibid. loc., same date, fl., Geay 8025 ( P) ; Bassin inférieur du Faraony , côte est, X.1911, fl., Perrier de la Bâthie 6695 ( P) ; N de Mahanoro , X.1921, fl., Perrier de la Bâthie 14521 ( P) ; Fkt. Ambalavontaka , forêt d’Antaimby , 20°22’22”S 48°33’16”E, 10 m, 16.IV.2004, fl., Razakamalala et al. 1109 ( MO, P) ; Fkt. Ampasimaneva , forêt d’Ambolo , 20°43’59”S 48°27’09”E, 13 m, 15.VI.2004, Razakamalala et al. 1473 ( MO) ; Fkt. Marohita , forêt d’Alimamba , 21°28’04”S 48°17’43”E, 13 m, X.2004, fl., Razakamalala et al. 1606 ( MO, P) ; Distr. de Mahanoro, Iambola [?], 14. III.1952, fl., Service Forestier 4902 ( P) ; Mananjary, Manampona , 7.I.1953, fl., Service Forestier 5621 ( P) ; Mananjary, Sakarivo , 23.III.1952, buds, Service Forestier 5642 ( P) ; Vohipeno, Analalava , 15.XII.1952, fl., Service Forestier 7093 ( P) ; Pangalane , S Mananjary, 24.II.1954, fl., Service Forestier 9513 ( P) ; Mananjary, Befoza , 25.III.1954, buds, Service Forestier 10174 ( MO, P) ; Mananjary, Ampangalana-Nord , 26.II.1955, fl., Service Forestier 13687 ( P) ; Nosy Varika, Ambohitsara I, forêt d’Analalava , 31.III.1961, fl., Service Forestier 19951 ( P). Prov. Mahajanga: Ankatsaka , 3.V.1952, fl., Service Forestier 5036 ( P). Prov. Toamasina: Betampona, piste principale, 17°55’S 49°13’E, 210-410 m, 25.IV.1994, fl., Andrianarisata 137 ( MO, P) ; forêt d’Analalava près de Foulpointe , 17°43’19”S 49°28’11”E, 250 m, 30.X.2000, fl., Andrianjafy & Rakotoarisoa 136 ( P) ; Fkt. Anamborano, près rivière Ihazoarina , à 10 km au N d’Anamborano , 17°42’04”S 49°00’48”E, 620 m, 12.VI.2004, fl., Andrianjafy et al. 441 ( MO, P) ; Fkt. Marovovonana, Ankirindro forest, 15°17’24”S 49°32’51”E, 584 m, 11.I.2003, fl. and post-fl., Antilahimena et al. 1693 ( MO, P) ; Foulpointe, X.1962, post-fl., Bosser 16993 ( MO, P [2 sheets]) ; Voie ferrée en allant de Tamatave , 13.X.1946, post-fl., Cours 2978 ( MO, P) ; road to Analalava , W of Foulpointe , 7.XII.1984, fl., Dorr & Barnett 3320 ( P) ; Passimbol [ Ampasimbola , 21.VIII.1881], fl., Humblot 34 ( P) ; Foulpointe [18. XII.1881], fl., Humblot 87 ( P) ; Antsianaka [17.XII.1882], st., Humblot 520 ( P) ; Andranokoditra, forêt de Vohibola , 18°34’26”S 49°14’36”E, 17 m, 14.XII.2004, fl., Lehavana et al. 231 ( MO, P) ; Tampina, XI.1925, post-fl., Louvel 35 ( P) ; Ambalahasina, forêt de Vohibola partie W, 18°32’S 49°14’E, 3-10 m, 26.X.2002, Ludovic 187 ( MO) ; Fkt. Andranokoditra, forêt de Vohibola (partie S), piste Ambodinanto , 18°34’20-53”S 49°14’42-54”E, 53 m, 7.I.2013, fl., Ludovic & Rakotoarivony 236 ( P) ; Fkt. Ambalavontaka, forêt d’Antaimby à 2.5 km au S d’Ambalavontaka , 20°22’58”S 48°33’14”E, 10 m, 13.II.2004, fl., Ludovic et al. 560 ( MO) ; Manompana, rivière Antsohy , 16°46’11”S 49°42’04”E, 8 m, 25.IX.2010, fl., Manjato et al. 251 ( MO, P) ; Near village of Antanambao-Ambodimanga, 16°45’39”S 49°42’29”E, 10 m, 19.V.2003, fl., McPherson et al. 18937 ( MO, P) ; Foulpointe , forêt d’Andranampango , 17°41’02”S 49°30’32”E, 12.I.2013, fl., Miandrimanana et al. 579 ( G, MO) ; Foulpointe , 22.XII.1995, fl., Pauly 756 ( P) ; Mahambo, distr. Fénérive , 12.VIII.1961, st., Peltier & Peltier 3422 ( P) ; Fkt. Andranokoditra, forêt CBD à Vohibola , 18°34’50”S 49°15’16”E, 10 m, 8.XII.2001, fl., Rabenantoandro et al. 820 ( MO, P) ; Fkt. Rantabe , 15°43’48”S 49°39’21”E, 5 m, 19. II.2002, fl., Rabenantoandro et al. 890 ( MO, P) ; Fkt. Andranokoditra, forêt de Vohibola , du côté de l’hôtel Pangalane , 18°35’32”S 49°14’02”E, 5 m, 11. II.2003, fl., Rabenantoandro et al. 1219 ( MO, P) ; Ankanin’ny nofy, forêt de Vohibola, 18°35’42”S 49°14’02”E, 10.II.2003, fl., Rabevohitra et al. 4388 ( MO, P) ; Mananara-Nord, sur sentier vers pk. 5 avant l’entrepôt Trans 7, 30.I.1990, post-fl., Raharimalala 169 ( P) ; Mananara-Nord, forêt de Beharamy (fkt. Sarahandrano ), 12.II.1990, fl., Raharimalala 279 ( P) ; Mananara-Nord, sur sentier pk. 5 à droite avant de passer l’entrepôt Trans 7, 27.II.1990, post-fl., Raharimalala 332 ( P) ; Tanambao-Ambodimanga, forêt de Menagisa-Pointalare [ Pointe à Larrée ], à 3 km vol d’oiseau au S de Tanambao Forêt , 16°46’35”S 49°41’20”E, 26 m, 9.IV.2011, fl., Randrianaivo et al. 1827 ( MO, P) ; Fénérive-Est, Tampolo Station Forestière , 17°17’00’’S 49°23’30”E, 10 m, 29.VI.1995, fl., Razafimandimbison 149 ( MO, P) ; ibid. loc., 17°17’20”S 49°25’37”E, 10 m, 30.VI.2001, fl., Razakamalala et al. 149 ( MO) ; Fkt. Ambalavontaka , forêt d’Antaimby , 20°22’21”S 48°33’15”E, 13 m, X.2004, buds, Razakamalala et al. 1579 ( P) ; Tampina, X.1924, fl., Réserves Naturelles (Dumazer) s.n. ( P) ; Distr. Tamatave, Ambatomanahafo , 11.III.1950, fl., Réserves Naturelles 2470 ( P) ; R.N. I [Betampona], 30.XI.1951, post-fl., Réserves Naturelles 3401 ( P) ; ibid. loc., 22.XII.1952, fl., Réserves Naturelles 4547 ( P [2 sheets]) ; R.N. II [Masoala], canton Ambohitralanana , 24.I.1953, post-fl., Réserves Naturelles 4939 ( P) ; Ambohitralanana, 19.XII.1956, post-fl., Réserves Naturelles 7973 ( P) ; Ambodiriana , 9.XII.1956, fl., Réserves Naturelles 8034 ( P) ; summit of massif of Ankirindro, ca. 25 air-km NW of Maroantsetra via the Antainambalana and Vohimaro rivers, 15°18’08”S 49°33’04” W, 671 m, 1.II.1999, fl., Schatz et al. 3921 ( G, MO, P) ; Ambila - Brickaville , 27.I.1951, fl., Service Forestier 1126 ( P) ; Ambila-Lemaitso , s.d., fl., Service Forestier 2105 ( P) ; ibid. loc., 22.I.1951, fl., Service Forestier 2990 ( P) ; ibid. loc., 17.IV.1951, post-fl., Service Forestier 3257 ( P) ; Ampanotoamazina, Ambila-Lemaitso , 14.VII.1952, fl., Service Forestier 5734 ( P) ; Ambila-Lemaitso, 17.XII.1952, Service Forestier 6456 ( P) ; Ambatomanasy [?], Maroantsetra , 16.XII.1952, fl., Service Forestier 7349 ( P) ; Bassin de la Mahalevona, massif d’Ansirosiro aux env. de [ Fizoana ], 400 m, date illeg., fl., Service Forestier 8733 ( P) ; JB-21 Tampolo , 10.IV.1954, fl., Service Forestier 10052 ( MO, P) ; forêt de Tampolo, 15.IV.1954, fl., Service Forestier 10070 ( P) ; Tampolo , 7.XII.1954, fl., Service Forestier 12487 ( P) ; Ambila-Lemaitso , sous parcelle F2K, 20.II.1958, fl., Service Forestier 19001 ( P) ; forêt de Mangalimaso à l’W de Foulpointe , 23.XI.1962, fl., Service Forestier 22089 ( P) ; env. de Chutes de la Mort (P.K. 51 de la route Moramanga-Anosibe ), 11.XII.1965, post-fl., Service Forestier 24388 ( P) ; Pangalanes Est, à la virge du lac Ampitabe , 15.I.1967, fl., Service Forestier 26234 ( P) ; Chaîne de collines d’Ankirihiry , à l’W d’Antetezana (S de Foulpointe ), 23.V.1969, fl., Service Forestier 28888 ( P [2 sheets]). Prov. unkown: sine loc., s.d., fl., Baron 5948 ( P) ; forêts côtières de l’E, s.d., fl., Louvel 199 ( P).